G'day Mark,
I did a similar thing with my wife's grade - but they were grade 5's not five-year olds. What I can suggest is to set up a couple of scopes if you have some friends around and get the kids to move from one to the other. I had my bigger scope fixed on Jupiter and my son had the smaller on the moon.
With a newly waning moon you should pick out any of the planets around, but don't forget the moon itself. I found kids and parents were absolutely fascinated by the moon since most of them had never look through a telescope. After Jupe disappeared I went to the moon with the bigger scope and they kept lining up! Talk to them and explain (in simple terms!) what they are looking at.
As others have said, the key thing will be keeping the five-year-olds interested...but the moon is a great draw card and they will keep coming back to look. So, the key is to keep each kid's viewing short so they want to come back and keep looking and their mates don't get bored whilst they are looking. The parents were equally fascinated and waited in line with the kids for their turn as well.
Oh, yeah...if you have a laser pointer the kids will be fascinated and you can show them and the parents what the correct use of the laser pointer is! It really helps when you point out constellations like Orion and the Cross.
Cheers and good luck!